Multi-Tech MultiModem EDGE Reference Manual page 123

Unsolicited Result Codes:
URC 1
Indication of a call that is currently waiting and can be accepted.
+CCWA: <calling number>, <type of number>, <class>, , <CLI validity>
If <n>=1 and the call waiting supplementary service is enabled in the network, URC "+CCWA" indicates a waiting
call to the TE. It appears while the waiting call is still ringing.
URC 2
Indication of a call that has been waiting.
^SCWA
If <n>=1 and the call waiting supplementary service is enabled in the network, this URC indicates that a waiting
call rang when the ME was in online mode during a CSD call, but the calling party hung up before the ME went
back to command mode.
Notes
•
If the active call is a CSD call, and a waiting call is received, then the ME produces a BREAK while still in online
mode, and displays
∗
the +CCWA URC (as above) when the ME goes back to command mode while the waiting call is still active
and can be accepted;
∗ or the ^SCWA URC (as above) when the ME goes back to command mode after the waiting call has ended.
•
With the AT+CHLD command, it is possible to establish a multiparty call or to set the active voice call on hold
and then accept a waiting voice call (not possible with data calls). See also AT+CHLD
• Users should be aware that if call waiting is activated (<mode>=1), the presentation of URCs needs to be
enabled, too (<n>=1).
Otherwise, on the one hand, a waiting caller would be kept waiting due to lack of BUSY signals, while, on the
other hand, the waiting call would not be indicated to the called party.
•
The AT+CCWA command offers a broad range of options according to the GSM specifications. However, when
you attempt to enable call waiting for a <class> for which the service is not provisioned or not supported, the
setting will not take effect regardless of the response returned. The responses in these cases vary with the
network (for example "OK", "Operation not allowed", "Operation not supported" etc.). To make sure check the
current call waiting settings with <mode>=2.
•
The AT+CCWA command has been implemented with the full set of <class> parameters according to GSM
07.07. For actual applicability of SS call waiting to a specific service or service group (a specific <class> value)
please consult table A.1 of GSM 02.04
• Despite the specifications stated in GSM 02.04 call waiting is not handled uniformly among all networks: GSM
02.04, Annex A, provides the following specification:
"The applicability of call waiting refers to the telecommunication service of the active call and not of the waiting
call. The incoming, waiting, call may be of any kind." Nevertheless, networks do differ on the actual
implementation of the service. Thus, the only reliable way to receive or prevent a call waiting indication under
any circumstances and in any network is to activate or deactivate call waiting for all tele- and bearer services
(<class> 255).
Examples
Example 1
Parameter <n>
at+ccwa=1
OK
Example 2
Parameter <mode>
at+ccwa=,1
OK
at+ccwa=,2
at+ccwa=1,1
at+ccwa=1,2
OK
Example 3
Parameter <class>
AT+CCWA=,0,1
OK
Multi-Tech Systems, Inc. AT Commands for EDGE Modems (S000371G)
Chapter 9 – Supplementary Service Commands
To enable the presentation of the URC
To activate the supplementary service in the network for voice and data calls.
(default classes).
Note that parameter <n> is left out. In this case, the current value of <n> will be
retained.
To query the network status of call waiting for default classes
Call Waiting is activated during voice calls.
Call Waiting is activated during data calls.
To deactivate call waiting for voice calls.
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